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Title: Hydrogen-Atom Transfer from Transition Metal Hydroperoxides, Hydrogen Peroxide, and Alkyl Hydroperoxides to Superoxo and Oxo Metal Complexes

Abstract

No abstract prepared.

Authors:
;
Publication Date:
Research Org.:
Ames Laboratory (AMES), Ames, IA
Sponsoring Org.:
USDOE Office of Science (SC)
OSTI Identifier:
909360
Report Number(s):
IS-J 7177
Journal ID: ISSN 0020-1669; INOCAJ; TRN: US200722%%1232
DOE Contract Number:
DE-AC02-07CH11358
Resource Type:
Journal Article
Resource Relation:
Journal Name: Inorganic Chemistry; Journal Volume: 46; Journal Issue: 7
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; HYDROGEN PEROXIDE; TRANSITION ELEMENTS; CHEMISTRY

Citation Formats

Michael J. Vasbinder, and Andreja Bakac. Hydrogen-Atom Transfer from Transition Metal Hydroperoxides, Hydrogen Peroxide, and Alkyl Hydroperoxides to Superoxo and Oxo Metal Complexes. United States: N. p., 2007. Web. doi:10.1021/ic070015z.
Michael J. Vasbinder, & Andreja Bakac. Hydrogen-Atom Transfer from Transition Metal Hydroperoxides, Hydrogen Peroxide, and Alkyl Hydroperoxides to Superoxo and Oxo Metal Complexes. United States. doi:10.1021/ic070015z.
Michael J. Vasbinder, and Andreja Bakac. Wed . "Hydrogen-Atom Transfer from Transition Metal Hydroperoxides, Hydrogen Peroxide, and Alkyl Hydroperoxides to Superoxo and Oxo Metal Complexes". United States. doi:10.1021/ic070015z.
@article{osti_909360,
title = {Hydrogen-Atom Transfer from Transition Metal Hydroperoxides, Hydrogen Peroxide, and Alkyl Hydroperoxides to Superoxo and Oxo Metal Complexes},
author = {Michael J. Vasbinder and Andreja Bakac},
abstractNote = {No abstract prepared.},
doi = {10.1021/ic070015z},
journal = {Inorganic Chemistry},
number = 7,
volume = 46,
place = {United States},
year = {Wed Jan 03 00:00:00 EST 2007},
month = {Wed Jan 03 00:00:00 EST 2007}
}
  • The superoxochromium complex Cr{sub aq}OO{sup 2+} abstracts a hydrogen atom from CMe{sub 3}CHO in acidic aqueous solution with k = 0.16 M{sup {minus}1} s{sup {minus}1}. This rate constant is only {approximately}10{sup 2} times smaller than that for the reaction of Cr{sub aq}O{sup 2+} with the same aldehyde, k = 23 M{sup {minus}1} s{sup {minus}1}, in contrast to the much greater reactivity difference between alkoxyl and alkylperoxyl radicals, k{sub t{minus}BuO}/k{sub t{minus}BuOO} {approximately}10{sup 6}. The absolute rate constants for hydrogen atom abstraction from a common reagent by metal-oxo and -superoxo species and the corresponding organic oxygen-centered radicals, RO{sup {sm{underscore}bullet}}, can now bemore » compared for the first time: k{sub BuO} (9 x 10{sup 7} M{sup {minus}1} s{sup {minus}1}) > k{sub CrO}(23) {ge} k{sub BuOO}(8) > k{sub CrOO} (0.16). The reactivity of individual species is explained by the energetics of the O-H bonds in ROH, ROOH, Cr{sub aq}OH{sup 2+}, and Cr{sub aq}OOH{sup 2+}.« less
  • TPPGe(OOCH{sub 2}CH{sub 3}){sub 2} (TPP is the dianion of tetraphenylporphyrin) which has remarkable thermal stability but is hydrolytically sensitive has been prepared by both reaction of ethyl hydroperoxide with TPPGe(OH){sub 2} and by photolysis of TPPGe(CH{sub 2}CH{sub 3}){sub 2} in the presence of dioxygen. The latter reaction involves successive reactions of the two ethyl groups to give TPPGe(OOCH{sub 2}CH{sub 3})(CH{sub 2}CH{sub 3}) and TPPGe(OOCH{sub 2}CH{sub 3}){sub 2} and the decomposition/hydrolysis products TPPGe(OH)(CH{sub 2}CH{sub 3}) and TPPGe(OH)(OOCH{sub 2}CH{sub 3}). X-ray diffraction studies on both TPPGe(OOCH{sub 2}CH{sub 3}){sub 2} and TPPGe(OCH{sub 2}CH{sub 3}){sub 2} confirm their similar, six-coordinate structures. The ring currentmore » shifted {sup 1}H NMR resonances of the axial ligands in these complexes are more effective than electronic spectra in monitoring reaction products. Photolysis of TPPGe(OOCH{sub 2}CH{sub 3}){sub 2} in toluene produces acetaldehyde and ethanol in ratios that are highly temperature dependent.« less
  • The addition of the methyl viologen radical cation (PQ/sup .+/) to solutions of V(H/sub 2/O)/sub 6//sup 2 +/ and hydrogen peroxide or alkyl hydroperoxide provides a method for measuring the initial reaction rate. The kinetic data so obtained are consistent with the rate equation -d(peroxide)/dt = k/sub 1/(V/sup 2 +/)(peroxide). Kinetic data are given for H/sub 2/O/sub 2/ (k/sub 1/ = 15.4 M/sup -1/ s/sup -1/ at 25.0/sup 0/C) and for RC(CH/sub 3/)/sub 2/OOH, with R = CH/sub 3/ (3.0 M/sup -1/ s/sup -1/), C/sub 2/H/sub 5/ (5.2 M/sup -1/ s/sup -1/), and CH/sub 2/C/sub 6/H/sub 5/ (4.8 M/sup -1/more » s/sup -1/). 27 references, 2 figures, 2 tables.« less
  • The anaerobic and aerobic decompositions of L{sub 2}Mo(O){sub 2}R{sub 2} (L{sub 2} = 4,4{prime}-dimethyl-2,2{prime}-dipyridyl, R = CH{sub 2}Ph, 1; R = CH{sub 2}C{sub 6}H{sub 4}CH{sub 3}-p, 2; R = (CH{sub 2}){sub 4}CH:CH{sub 2}, 3; R = CH{sub 2}CHMe{sub 2}, 4; R = CH{sub 2}CMe{sub 3}, 5; R = CH{sub 2}CMe{sub 2}Ph, 6) were studied. The anaerobic decomposition mode chosen by a given L{sub 2}Mo(O){sub 2}R{sub 2} complex is a sensitive function of the hydrocarbyl group, R. If accessible {beta}-hydrogens are present on R (as in 3 and 4), equal amounts of alkane and alkene are formed through a {beta}-hydrogen abstractionmore » pathway. In the case of 4, an additional pathway involving Mo-R bond homolysis accounts for 10% of the products formed. When {beta}-hydrogens are absent from R (as in 1, 2, and 6), the free radical, R{sup {sm bullet}}, formed by Mo-R bond homolysis is the predominant product. The reaction of the L{sub 2}Mo(O){sub 2}R{sub 2} complexes with O{sub 2} appears to proceed almost exclusively through the intermediacy of the free radical, R{sup {sm bullet}}. In inert solvents, the principal organic product is the corresponding aldehyde, and the role of O{sub 2} in its formation from L{sub 2}Mo(O){sub 2}R{sub 2} is 2-fold: (a) O{sub 2} promotes the homolysis of the Mo-R bond to form R{sup {sm bullet}}, and (b) O{sub 2} traps the resultant radical to yield the aldehyde. Labeling studies indicated that O{sub 2}, rather than the Mo{double bond}O group, was the predominant source of oxygen for the aldehydes. Mechanistic implications of the authors' observations for the heterogeneous oxidation of alkanes and alkenes by Mo(VI)- and V(V)-oxo species are discussed.« less